1. Field of the Invention
This invention relates to liquid dispensing pump devices for use with liquid consumer product containers; more particularly, to such liquid dispensing pump devices which utilize a collapsible pump chamber (e.g., a bellows).
2. Description of the Prior Art
Known liquid dispensing pump devices for use with consumer product containers are many and varied. Such dispensing pumps may be utilized to deliver liquids as a foam, a spray, or a liquid stream (e.g., as with moisturizing lotions), for example. Most commonly, such liquid dispensing pump devices utilize a piston and cylinder pump chamber. Such pump chambers require that a liquid tight moving seal be maintained between the piston and the cylinder. Disadvantages are commonly associated with this liquid tight seal requirement. For example, a relatively large amount of friction is generated as the piston moves against the cylinder, since these parts must fit tightly to form the seal. Additionally or alternatively, the parts themselves must be manufactured within tight tolerances such that the parts fit correctly to form the seal. Moreover, the wear caused by the friction can deteriorate this seal over time, reducing the efficiency of the pump. Furthermore, these piston and cylinder dispensing devices have generally been designed without significant effort to reduce the number of parts and overall cost.
In addition to piston and cylinder-type pumps, several liquid dispensing pump devices have been developed which utilize pump chambers with collapsible walls which overcome some of the disadvantages of piston and cylinder pump chambers. For example, balloon type pump chambers have been utilized. More commonly, flexible, resilient bellows have been utilized as collapsible pump chambers in liquid dispensing pump devices. Such bellows-type pumps permit the pump chamber to expand and contract in volume without the disadvantages associated with the moving seal required in piston and cylinder pumps. Furthermore, the bellows can replace the piston, the cylinder and the spring; thereby reducing molding and assembly costs. These prior liquid dispensing pump devices, however, do not offer all of the advantages of the invention described herein.